Just before Ottway stumbles into the wolf den, he is trudging alone holding Henrick's pack in his right hand. The angle cuts as he leans on a tree with his left hand, and it's clearly seen that he's holding the pack with that hand. Immediately after, it's in his right hand again.
When Ottway jumps into the rushing river to save a friend, he would not have been able to stand the freezing cold water for more than a minute. Afterwards, he lifts himself out of the water and continues his quest. Hypothermia would have killed him within minutes after leaving the water,
Before setting off for the woods, Ottway searches through the plane wreckage and finds his rifle in its case, with the stock broken in two. He then discards the rifle. This is strange as, even with the stock broken and scope ruined, it would be possible to fire the rifle with reasonable accuracy at close range, certainly accurately enough to dispatch a number of wolves.
Unfortunately, planes are far more valuable than people. Whatever the reason that oil workers might not have been missed, their plane would have been (by its owners and the insurers) and a search for it would have been undertaken within HOURS of it not arriving at its destination. Additionally all US aircraft are required to have and maintain ELT (emergency location transmitters) which would help find the plane if it is lost. While this device might destroyed in the crash, this happens very few times when a plane has an accident in manner depicted in the film.
The goof item below may give away important plot points.
Just before Flannery gets killed, the other six men are walking through a heavy blizzard with strong winds but when they run back to Flannery after the attack and kneel beside him there is almost no wind at all.